How to call host page javascript function inside iframe?

parent.testmethodname();

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http://www.eggheadcafe.com/tutorials/aspnet/b480ba4e-b59c-43d4-ac4b-2990ca19daec/restful-aspnet-wcf--jquery--json-service-with-get-post-put-and-delete.aspx

Using JQuery Validation With ASP.NET Web Forms

Using JQuery Validation With ASP.NET Web Forms